A Visit From The Past: A BBC Sherlock and Mass Effect Crossover
by mythlover20
Summary: The fight with the Reapers is going badly, and Shepard needs help. Luckily Mordin has been bored, and has invented something very, very, unusual, and previously thought impossible: A TIME MACHINE! So Shepard uses it to recruit the one man who could make sense of the wasteland of the Prothean Data Cashes the Shadow Broker couldn't. SHERLOCK HOLMES, plus friends! Rated T for now.
1. Chapter One

**A Visit From The Past**

**Part Two**

**Mass Effect x BBC Sherlock Crossover Fanfiction**

**Written by AseniaKarana (subaruchan192) and mythlover20**

* * *

**The fight with the Reapers is going badly, and Shepard needs help. Luckily Mordin has been bored, and has invented something very, very, unusual, and previously thought impossible: A TIME MACHINE! So Shepard uses it to recruit the one man who could make sense of the wasteland of the Prothean Data Cashes when the Shadow Broker failed. Plus his friend, and maybe a few others she did not intend to bring along.  
**

**Part One of my little sister's and my BBC Sherlock and Mass Effect Crossover. This is the result of one of our 2AM chat sessions, that sort of ballooned out of control because it was just too awesome an idea. This was written mostly for people who are fans of both ME and Sherlock, as we do not dip into their lores in-fiction, but if anyone needs clarification just send me a pm and I'll answer any questions in the A/N.**

**At the time we started writing this she and I were the ONLY people in the entire Sherlock fandom to do a Mass Effect Crossover, so hopefully, you will all like it.**

**Sort-of loosely following the events of ME3, but rewriting a lot and fixing as many mistakes that BioWare made as we can. Especially the two big ones. Cheers! xoxo  
**

* * *

Shepard: *Stands in front of a large device* So, here we are.*Watches Mordin fiddle with the front of the device, at a control panel of sorts. Her eyes follow him as he moves around the tube-like structure, checking connections to the drive core, the cooling system, and EDI's computer backs.* This is gonna be interesting."

Thane: *Stands next to Shepard, staring skeptically at the huge metal tube.* What are you going to do with it, Siha?

Shepard: I'm gonna bring someone here, who might help us against the Reapers.

Thane: Someone from the past?

Shepard: *shrugs* Of course. If not, I would not need a time machine, right? *Crosses her arms and looks at the appeature of the strange machine, trying to guess how it works* Do you think Mordin could have just written an instruction manual? No, wait. It's probably better that he didn't. I doubt I could understand his fragmented sentences.

Mordin: *Stands, and turns to Shepard.* It is ready. What time is needed, Shepard?

Shepard: *Thinks for a while, tilting her head left to right.* Well... 2015... London. 221B Baker Street. Say… midday, April the 15th?

Mordin: *Whistles a little melody while entering the data into the machine.* He pulls a lever, pushes some buttons, then stands back, waiting.*

Thane: Who are you bringing back?

Shepard: Wait and see. Cortez, Vega, be ready for anything. We don't know if it's going to work.

Cortez and Vega: Aye, ma'am!

Mordin: *Smiles at Shepard.* Doubting my abilities, Shepard?

Shepard: *Smiles back at Mordin and shakes her head.* Never, Mordin.

Thane: I have a bad feeling about this.

Shepard: *Lightly rests a hand on Thane's arm.* It will be fine. If this works, these people I'm bringing in will be able to help us.

Thane: *Sigh* I do hope you're right, Siha.

Shepard: *Gently squeezes Thane's arm before letting go. She crosses her arms and rests back on her right leg. She turns to Mordin.* All right, Mordin. Light her up.

Mordin: *Nods enthusiastically.* Yes, Commander. *Pushes one last series of buttons, and stands back away from the machine.*

*The machine comes to life, lights flashing and the exposed gears turning. Suddenly the shuttle bay goes dark, and sounds from the engine stop. A small fire catches light on one of the cables connecting the machine to EDI's core, via an access panel in the wall. James grabs a nearby fire extinguisher and rushes over to put it out. Smoke and fire retardant fill the bay, cloaking the machine and the people surrounding it from view. James manages to put the fire out, and stumbles back to his previous position, extinguisher in hand in case it was further needed.

*Shepard reaches out and grasps Thane's hand just as the lights flicker back on, and the noise of the drive core softly vibrates throughout the ship. Shepard breathes a sigh of relief.

*Immediately all look towards the time machine. Grey smoke surrounds it, obscuring the open door from view. Shepard releases Thane's hand, and takes a step closer. She motions with her hand for Vega and Cortez to ready weapons. She steps closer still, and tries to peer into the fog.

*Suddenly a shadow appears, hunched, stumbling forwards. Immediately behind it a second appears. Shepard retreats back to Thane's side. Vega and Cortez move into position, weapons ready. Thane's hand flairs slightly with his biotics. The shadows stumble closer still. Shepard raises a hand, ready to give the order to fire.

The shadows cough. Shepard frowns, lowers her hand, and waits for them to come to her.

The tall figure stumbled out first. At first glance it appeared human, tall but emanciated. He had a mop of curled brown hair, longer than was fashionable for human men. The second figure too appeared human, though shorter, blonde, and with a fashionable military hair cut. The clothes they wore, too, were unfashionable for humans, almost vintage in appearance. A long coat and scarf were all that were visible on the tall human. One the second trousers and a think jumper and jacket were easily distinguishable. Both were still hunched over, coughing, unhearing and unseeing of anything around them, aware only of each other.

Shepard: *Whispers* It's them. It worked. *Smiles slightly* It's them: Holmes and Watson.

Sherlock: *Steps out of the fog that surrounds the time machine, coughs horsely, then immediately straightens and loosens the scarf around his neck. Takes a quick look around, but sees nothing but John in the fog.*

John: *Coughs and tries to wave the smoke away, and fails. Says in a hoarse voice.* Sherlock, what the hell was that? It's foggier here than on the river bank at dawn.

Sherlock: *Squints and tries to look through the fog. Shakes his head, and replies equally hoarsely.* I have no idea...but it looks like we were transported into one of your stupid science fiction movies, John. *Sarcastically.* Maybe were going to meet Spock?

John: *Stares pointedly at Sherlock.* Are you on drugs again?

Sherlock: *Rolls his eyes.* Oh, don't be silly. Of course not! That would mean you are as well.

John: *Blinks* Well, that has happened before…

Thane: *Frowns at the two new, strange humans.* Siha...who are they?

Shepard: *Gestures grandly to the smoking time machine* Thane, my love, say hello to the most famous detective in human history: Sherlock Holmes!

John and Sherlock: *Hear the voices behind them. They turn, and stare, stunned.*

John: Ah, Sherlock? Who are they?

Sherlock: I think the more appropriate question would be "What" are they?

John: You know what I meant.

Sherlock: Of course I know. I'm not stupid.

John: Well...

Shepard: *Steps forward towards the two stunned men.* Mr. Holmes. Doctor Watson. Welcome to the 23'rd century. I've brought you here because we need your help.

Sherlock: *Shakes his head and frowns.* Funny. Even illusions need my help these days.

John: *Addresses Sherlock but continues to stare at the people in front of him.* Wow... then this a strange trip. Maybe molly slipped something into our coffee.

Sherlock: *Shakes his head and turns his back to the "apparitions" surrounding him.* No. Molly wouldn't do that. Too forceful for her. She's not into petty revenge.

John: I don't know.

Sherlock" *sigh* She still hasn't forgiven me.

John: *Looks back at Sherlock.* I wouldn't have forgiven you either, after that.

Sherlock: *Hums indifferently and looks around.*

John: She was in love with you, Sherlock. *Mutters* Though God only knows why.

Sherlock: *Sighs* Which is why she wouldn't do this. Someone else must have drugged us, but who..?

Shepard: *coughs repeatedly to gain Sherlock and John's attention* Uh, hello? You can see us, right?

Sherlock: *Spins back around and yells at Shepard.* Oh, shut up! I don't have time for petty illusions.

Shepard: We aren't illusions. We're real, and you're in the future.

Sherlock: I highly doubt that. Time travel is impossible. *turns back to John* Now, think, John, think! Who would do something like this? Who would have access to the morgue, the tea room, and who can get by the staff unseen. The janitor? No, he's been there for years. He would have done this by now…

Thane: *to Shepard* I'm not quite sure that this was a good idea, Siha.

John: *Turns around, and gets a good look at Thane. He jumps.* Jesus! What the fuck is that?

Sherlock: *Sighs* Only just noticing now, John?

Thane: *Sighs as well.* I am a drell.

Shepard: Look, I understand that this may be a shock for you, but this is real. We are not a delusion. Just relax, and everything will be fine. *Looks to Mordin* Mordin? Could you make sure they're all right.

Mordin: Of course, Shepard. *Mordin moves closer to John and Sherlock. He raises his arm towards John to take a scan.

John: *Draws his handgun and points it at Mordin* Don't move!

Shepard: *raises hands* Calm down. We're not going to hurt you!

Mordin: Violence unnecessary. Collecting medical data. Biorhythmic scans. Nothing to cause harm.

John: Yeah, I'll be the judge of that.

Shepard: We brought you here for your help, not to hurt you. Put the gun down, and we'll talk about this.

John: Oh, no. I don't think so.

Sherlock: *Looks around. Notices the armed marines with strange weapons pointed at them.* Put the gun down, John.

John: Not bloody likely.

Sherlock: *Moves closer to John* Do you really think your handgun will be of much use against _those_. *Nods towards Vega, Cortez, and the armed marines behind them.*

Shepard: *Takes a step closer towards John* There are half a dozen marines surrounding you with Avenger assault rifles. Be smart, and put the gun down, Captain.

*John glances around, and realises the situation. He begins to lower the gun. Mordin takes another step closer, and raises his arm again to take his scans. John jerks back, and instinctively raises his arm again. Thane reacts, and disarms John. Sherlock tries to defend John from Thane. The two humans attempt to fight Thane.*

Shepard: *sigh* Mordin? Do you mind? Before someone gets hurt.

*Mordin nods, and raises his arm. Thane jumps back, and Mordin releases a mild neural shock. Sherlock and John twitch, and fall to the floor, unconscious.

Thane: *Sighs* Are you still sure this was a good plan, Siha?

Shepard: *Groans* Not anymore, but I'm getting desperate. *She gestures behind her to Vega and Cortez* Vega! Cortez! Take these two up to the med bay and restrain them.

Vega: Sure thing, Lola.

Cortez: Yes, Commander.

*Vega and Cortez lift the two men and carry them to the elevator.*

*Thane hands Shepard John's gun.*

Thane: Are you certain these are even the men you were looking for?

Shepard: *Looks down at the gun.* British Army Browning L9A1, issued to British Army officers service in Afghanistan during the early 2000s. Yeah. I'm sure.

Thane: I hope you know what you're doing.

Shepard: *looks up at Thane* Doubting me, Thane?

Thane: *Looks at Shepard. Smiles.* Never, Siha. *Looks towards elevators* Them? We'll see…


	2. Chapter Two

**A Visit From The Past**

**Part Two**

**Mass Effect x BBC Sherlock Crossover Fanfiction**

**Written by AseniaKarana (subaruchan192) and mythlover20**

* * *

**The fight with the Reapers is going badly, and Shepard needs help. Luckily Mordin has been bored, and has invented something very, very, unusual, and previously thought impossible: A TIME MACHINE! So Shepard uses it to recruit the one man who could make sense of the wasteland of the Prothean Data Cashes when the Shadow Broker failed. Plus his friend, and maybe a few others she did not intend to bring along, now including the most dangerous man she is ever going to meet.**

**Part Two of our little fic and Sherlock and John wake to find that no, they are not drugged, and things are a lot worse than they initially seemed.**

**Well, Sherlock may be drugged. Who knows how many nicotine patches he has under those sleeves.**

* * *

*Vega and Steve enter the Medical Bay. Only the humming of the E-Zero Core is audible as they lift Sherlock and John onto the examination tables. Shepard, Mordin and Thane follow, watching the new arrivals closely.*

Shepard: You can go, Vega, Steve. Guard Mordin's… device.

Vega and Steve: Yes, Ma'am! *Vega and Steve leave the Med Bay*

Shepard: Mordin? Could you please check to see if they're alright.

Mordin: Yes, yes. *He activates his omnitool, and runs it over Sherlock's prone form.* Vitals good, no signs of stress... will be awake soon. *He moves to John's bedside, and raises his omnitool to scan the second unconscious human.*

Shepard: *Sits down in one of the chairs in front of Dr Chakwas' desk, beside Thane. Turns to him.* Thane, maybe you should have your check up now. It was due today anyway.

Thane: *Briefly takes his eyes off of Sherlock and John to look at Shepard.* Are you sure, Siha?

Shepard: *Nods, and gently runs her hand down his arm.* Yeah, you might as well. Who knows when "soon" will be.

Thane: *Nods and rises, walking over to Dr. Chakwas. Sparing glances at the two strangers he proceeds to prepare for the examination, removing his jacket and placing his sidearm on the bed beside him.*

Doctor Chakwas: *Smiles reassuringly at Thane.* Don't worry, Thane. We won't be requiring needles for this examination.

Thane: You must be so disappointed.

Chakwas: Oh, I am.

*Shepard smiles at Thane's and Chakwas' banter. Over their voices she hears a moan. She turns back to the two men on the examination tables. Both were beginning to wake.*

*Sherlock blinks his eyes, squinting against the harsh light. He opens them, and turns his head to one side. He sees equipment he has never seen before filling a room he has never been in before. He turns his head to the other side. John lies in a bed next to him, moaning.*

John: *Raises a hand to his head.* Well, that was a bad trip.

Sherlock: Are you all right?

John: *Groans.* My head feels like its got a jackhammer pounding inside it…

Sherlock: You'll be fine, then. *Sees Mordin scanning John and smiles slightly.* I guess it's not over yet. *He nods, gesturing to the creature standing next to John.*

John: What? *Turns his head to see Mordin standing beside him. His eyes widen.* He...hey! What are you doing?

Shepard: *Rises from the chair and moves to stand centred between Sherlock's and John's beds.* Mordin's just checking that there are no consequences from the neural shock. How are you feeling? Apart from the head?

John: Who? Me? Oh, I'm fine. Except that I'm surrounded by freaks of nature!

Sherlock: John!

Shepard: *Smiles softly.* It's quite alright, Mr Holmes. I've been called worse in my day.

Sherlock: You should learn to assess the situation more neutrally, John. And to control your temper.

John: I'm surrounded by two - what? Aliens that look like lizards? - and you want me to control myself?

Thane: *Frowns at the wall behind Dr. Chakwas as she runs her scans.* I'm a Drell. I do not know what a "lizard" is.

Shepard: *Smiles cheekily.* Oh, it quite fits, Thane.

Thane: *Raises a brow ridge at her.*

Shepard: *Turns back to John and Sherlock.* I understand your confusion; this is a very strange situation for you, but I do need you to focus and accept this as real. *Leans back on her leg and folds her arms across her chest. She takes a deep breath.* You are on a spaceship, gentlemen. A frigate called the SSV Normandy SR2 in the Earth Systems Alliance military. Since your time humans have discovered what we call "mass effect" technology. This has allowed us to explore and colonise the galaxy, thus joining a pre-existing wider galactic community made up of many sentient races. Since then this galactic community ha…

Sherlock: *Sits up on the bed and waves his hands dismissively, interrupting Shepard.* So, what? You're a highly educated black ops marine in command of her own state-of-the-art vessel, two scientists, one of whom is a doctor capable of effectively treating multiple species, and presumably the best crew you can get that obviously isn't limited to just our own species. Why would you need our help?

John: *Stares at Sherlock in shock.* Sherlock! You seriously believe all this? I mean… she's talking about _time travel!_

Sherlock: *Stares at John warningly.* Look around you, John. What evidence can you see that would refute her claims?

John: *Looks around the room.* Well, there's, um…

Sherlock: And what about the two aliens in the room, hmm? How would you explain them?

Shepard: *Sighs loudly and looks at John.* Alright, that's enough. Captain Watson, please, I know this is difficult for you but it's only going to get worse if you don't listen to me now. *Turns back to Sherlock.* As for why we need your help… it's difficult to explain, but we need your abilities, Mr Holmes. We need your mind. *Takes another deep breath.* We're at war. Everyone, not just humans. The entire galactic community is…

*A disembodies voice speaks over a hidden intercom system.*

EDI: Shepard?

Shepard: *Sighs in exasperation and looks up at the roof.* Yes?

EDI: We have a problem.

Shepard: What kind of problem, EDI?

EDI: There is another one.

Shepard: Another what?

EDI: Another unidentified human has appeared in the hanger.

**~*~ Meanwhile, in the Shuttle Bay ~*~**

*A third figure appears in the smoke surrounding the time machine. Coughing, waving his hand to clear the smoke, he looks around, leaning on a long, slender object. He frowns, confused.* Well… this was unexpected.

Marine: Don't move!

**~*~ Back in the Medical Bay~*~**

Shepard: What? *Shepard looks at Mordin.* How could that happen?

*Mordin shrugs.*

EDI: A third energy wave emanated from the temporal device. It appears to have captured another human.

Shepard: *Shakes her head.* Shit. Do we know who it is, or where, or when, they're from?

EDI: No... All I can say is that his physical appearance suggests a time period similar to that which our current guests have travelled from.

Shepard: Is he armed?

EDI: Negative. He is, however, carrying what my data calls an "umbrella."

*Sherlock and John exchange a glance. John raises a questioning eyebrow. Sherlock shrugs.*

John: Do you think it could be Mycroft?

Sherlock: *Snorts.* Oh, I wouldn't be surprised at this point.

Shepard: *Frowns.* Who?

Sherlock: *Sighs dramatically, closes his eyes and temples his fingers under his chin.* The most dangerous man you could ever meet. You have made a big mistake bringing him here.

*John frowns, rolls his eyes, and groans loudly. Sherlock throws him a indignant glance, before lowering his hands into his lap.*

Thane: *Turns around on his table and stares at Sherlock and John suspiciously.* Do you want me to investigate, Siha.

Shepard: *Glances at Thane and shakes her head.* You're not getting out of your check up that easily, Krios. *Looks back up at the roof.* EDI, tell Vega and Steve to escort our new guest to the Medical Bay.

EDI: As you wish, Shepard.

Shepard: *Turns back to Sherlock.* Exactly what did you mean by that statement? Who is this man?

Sherlock: I told you exactly who he is. Do try to keep up.

*John shakes his head in exasperation.*

*Shepard stares at Sherlock and John sitting on their beds in silence. A few minutes later the Med Bay door opens. Vega and Steve return guarding a third, well-dressed individual. The new human spies Sherlock and John on the beds, stops short, and raises an eyebrow. Sherlock groans. John closes his eyes and rests his head his hand. Mycroft continues to scan the room, his eyes widening at the sight of the two alien creatures in the room. He grips his umbrella tightly before turning his eyes back to Sherlock. Shepard signals Vega and Steve to stand guard inside the door, and studies the new arrival in silence.*

Mycroft: * Blinks.* Well, Sherlock, what you have gotten yourself into, now?

John: *Murmers.* Another bloody battleground is what.

Mycroft: Life is a battlefield, Dr. Watson. You know that.

Shepard: *Clears her throat.* "Mycroft," I assume?

Mycroft: *Eyes Shepard, examining her, before giving her an insincere smile and offering her his hand.* And you, I presume, are the captain of this unusual vessel. I see my baby brother has been talking about me.

Shepard: *Raises an eyebrow.* Brother? He described you as the most dangerous man I would ever meet.

Mycroft: Of course he did.

Shepard: Are you?

Mycroft: *Smiles and releases Shepard's hand.*

Shepard: *Narrows her eyes and stares suspiciously at Mycroft.* Right… So if there are no other random ancient humans popping into my shuttle bay I will like to explain this situation properly. *Gestures at Mordin.* If you please…

*Mordin moves from John's side, and runs his scanner over Mycroft. Mycroft jerks back, and glances around, but reluctantly allows it.*

Shepard: Now, where was I? Oh, yes. You have all…

*A loud alarm tone sounds throughout the Normandy*

John: *Looks around.* What's this?

EDI: Shepard, we have a problem! The system is under attack!

Joker: Five Reapers have entered the system, Commander. Two are heading straight for Dekuna!

Shepard: Dekuna? Fuck! Fuck! Fuck!

John: Reapers? What is a Reaper?

Shepard: Shit! I'll explain later. Vega! Guard these three!

*Vega nods.*

Shepard: *Hastens over to Thane, placing a hand on his arm while addressing the air.* Joker, activate stealth mode and execute evasive manoeuvres!

Joker: Yeah, already knew that, Shepard!

Shepard: Garrus?

Garrus: Yes, heard it, Shepard. On my way.

Shepard: Meet you in the shuttle. *Gives Chakwas a look. Chakwas nods, putting away her instruments. Shepard turns to Thane.* Thane, you up for this?

Thane: Of course, Siha. *Picks up his coat and grabs his sidearm.*

John: *Looks around in confusion.* What the hell is going on?

Shepard: *Rushes through the medical bay, followed closely by Thane.* Cortez, get the shuttle ready. Vega, I'll send a marine to relieve you. As soon as he arrives, defend the trade floor.

Vega and Steve: Yes, Ma'am!

*Shepard and Thane immediately run to the elevators, and out of sight. Three minutes later a new marine arrives, and replaces Vega. Vega also runs from the Medical Bay, and soon disappears from sight.*

Sherlock: *Watches it all thoughtfully.* I guess she was not exaggerating when she was talking about a war.

Mordin: Galactic war. Against synthetic aliens.

John: * Stares with widened eyes, but says nothing.* …

*Mordin nods emphatically, and deactivates his omnitool. Mycroft breathes a sigh of relief as the alien moves away.*

Mordin: *Gestures towards the door.* Should show you. Come with me. Come! Must see this. *Mordin leaves the Medical Bay in a rush.*

Sherlock: *Jumps from the bed and to his feet, stumbling slightly due to the neural shock. He follows Mordin, sarcastically patting Mycroft on the shoulder.* Synthetic aliens? This might be interesting.

Mycroft: *Sighs and shakes his head, but silently follows after Sherlock.*

John: *Shakes his head, climbs off the bed, and slowly follows after Mordin, Mycroft and Sherlock. Mumbles.* This is a bad dream. A nightmare. It has to be…


End file.
